Check a teammate's branch is unmerged before reviewing it

git log origin/master..origin/feature can list commits that were already squash-merged, because a squash merge creates a new commit and the originals never become ancestors of master. Before reviewing or merging such a branch, run git diff --stat origin/master origin/feature. Empty output means its content is already in master. For a quick conflict check against your own branch without touching the worktree, git merge-tree --write-tree --name-only A B lists the conflicting paths.